This invention relates generally to apparatus for producing sheets of corrugated board and the like and more particularly relates to a multiple station slitter scorer in which the heads are power adjusted.
Corrugated board is produced as a relatively wide web which is cut longitudinally by a slitter scorer into a plurality of narrow webs that are subsequently cut transversely into sheets. The slitter scorer also indents or creases the board, when necessary, to facilitate subsequent folding operations.
To prevent excessive downtime of the very expensive corrugator and related machinery when adjusting the slitter scorer for a new order, normally the latter is constructed to have a plurality of stations one of which is adjusted for the next run while another station is operating on the wide web. For the most part, prior art slitter scorers were constructed so that the stations were movable to a single paper line along which the web traveled through the slitter. At the same time the station having the cutting and creasing heads to be adjusted for the next run was moved to an advantageous position for head adjustment. In a typical plant, slitter scorers have to reset or adjusted 30 times for an 8 hour shift. Most prior art slitter scorers required that the head pairs, typically a total of 13 pairs for each station, be adjusted individually and manually with the operator being required to perform these adjustments in relatively tight quarters close to rotating slitter and creaser heads so that adjustment was an unpleasant and time-consuming operation. Because of this the prior art has attempted to provide power driven adjusting means.
A power driven adjusting means for slitter heads is disclosed in U.S. Pat. No. 3,646,418, issued Feb. 28, 1972, to R. B. Sterns et al. for "Positioning of Multiple Elements". In the device of the Sterns et al. patent an individual adjusting mechanism is provided for each head pair with the multiplicity of head adjusting devices making the apparatus relatively expensive. Further, controls must be able to determine the motions of all head adjusting devices simultaneously. This requires either a separate sensor in each head adjusting device or at least separate controls for starting and stopping each head adjusting device. Utilizing separate controls on each head adjusting device requires all the devices to be driven by a common lead screw in order that a single sensor be used. With a single sensor arrangement of this type revolutions of the lead screw are counted between the time a given head adjusting device is engaged with the lead screw to the time when the device disengages from the lead screw. The power driven adjusting means of the aforesaid U.S. Pat. No. 3,646,418 required two cycles of operation to set-up a single station. First, the slitters or scorers were positioned and then the entire power driven adjusting means had to be moved bodily for engagement with and set-up of the remaining slitters or scorers.
The prior art, upon realizing the deficiencies of the foregoing approach including means for independently engaging and disengaging each head adjusting device with the lead screw and means for automatically controlling these engaging and disengaging devices, all of which adds considerably to the expense of the apparatus and the likelihood of failure, provided a single head adjusting device for each station constructed so that it selectively engages each head pair to sequentially move the head pairs to selected positions along the lengths of their drive shafts. While the single head adjusting device engages the heads in sequence, a degree of simultaneous adjustment is obtained in that while the device engages and moves one head this head may impart motion to an adjacent head moving the latter toward its position.
Examples of a single head adjusting device for sequentially engaging a plurality of head pairs are found in U.S. Pat. No. 4,033,217, issued July 5, 1977 to S. S. Flaum et al. for "Slitter Having Carrier for Selective Adjustment of a Plurality of Heads" and U.S. Pat. No. 4,214,495, issued July 29, 1980 to R. E. Coburn for "Slitter Scorer Apparatus". While the devices of the aforesaid U.S. Pat. Nos. 4,033,217 and 4,214,495 provide automatic adjusting means of reduced cost, they do so at the expense of excessive size, difficulty of manual adjustment and costs that should be further reduced. In addition, because the stations of these devices are necessarily large, it would be cumbersome and costly to move them. Instead, they are fixed in position one above the other; means are therefore required for shifting the paper line up and down so that it extends through the station being used to slit and score the web. This vertical movement of the paper line is normally done while the machine is running to avoid wasting time and disrupting process parameters, but control of the paper path is sometimes lost during this vertical movement, with the result that the machine jams, wasting paper and losing production time. That is, each of these constructions requires a separate adjusting means for each four shaft or bar slitter scorer station, with one adjusting means being disposed above the paper line and the other below the paper line. The adjusting means and their associated head pairs are not readily accessible for servicing and/or manual adjustments. The foregoing results in part because the stations are located one above the other and they are in fixed vertical positions.
Even when the prior art has sought to provide movable stations and utilize a single automatic adjusting means, the result has been that the automatic adjusting means is split so that there is a portion below the paper line as well as a portion above the paper line. This adds to costs of construction, and the split adjusting means makes manual adjusting difficult especially for the portion above the paper line. An example of the latter type of construction is found in U.S. Pat. No. 3,587,374, issued June 28, 1971 to W. A. Stewart et al. for "Presettable Slitter-Scorer Apparatus". This prior art construction has the slitters and scorers mounted on different rotatable carriers so that there must be considerable spacing between them.